Israeli military officials claim troops only fired warning shots, but local media report at least four people were killed when protesters attempted to cross the border on Sunday.

Pro-Palestinian demonstrators also came under-fire after approaching from the border from neighbouring Syria.

Palestinians are today marking Nakba Day â their term for the founding of Israel in 1948.

Earlier on Sunday, Israel fired two tank shells and several rounds from machine guns as Gazans approached the heavily fortified border with Israel, wounding at least 15 youths.

The clashes have been taking place at four separate border crossings, with commentators claiming the pro-Palestinian demonstrators have been given extra impetus following the recent uprisings in north Africa and the Middle East.